I'm reading a book on harmony and I got to the section on raised sixths and sevenths in minor keys. Here are some of the seemingly arbitrary rules it gives:
1. If V-VI, raise the 7th
2. If V6-VI, don't raise the 7th
3. If V6-IV, then whether the 7th is raised or not depends on whether the bass rises or falls
4. If V6-IV6, 7th always unaltered
5. If V6-II6, only raise if bass rises
6. If IV6 moves to V6 or VII, then always raise 6th and seventh
7. If IV6 moves to III, III6, V, or VI, then don't raise the third of IV6
It's a lot easier to digest and remember rules when there is some kind of logic or principle behind them. But I fail to see the logic in these rules? Can anybody help?
